1. Field
The following description relates to a signal demodulation method and apparatus and a signal modulation method and apparatus, and more particularly, to a method and apparatus for demodulating a burst, which can increase transmission efficiency in a return link, and a method and apparatus for modulating the burst.
2. Description of the Related Art
Time division multiple access (TDMA) is a channel access method for shared medium networks, which allows multiple base stations to share the same frequency channel by dividing a signal into different time slots. TDMA is used for digital cellular phone communication. Particularly, multi-frequency time division multiple access (MF-TDMA) is a leading technology for dynamically sharing frequency band resources in an over-the-air and two-way communications network. Various MF-TDMA technologies have been widely used for multiple networks.
An MF-TDMA based digital transmission system essentially requires burst synchronization technology for a receiving end to determine a burst starting point, a carrier frequency error estimation and correction technology, a symbol timing synchronization technology, and the like. There is a rising need to increase band efficiency per bandwidth more than the conventional digital video broadcasting-return channel by satellite (DVB-RCS) and strengthen competitiveness to the very small aperture terminal (VSAT) standards.
Hence, to take into consideration both a linear modulation technique that is a physical to layer specification of Digital Video Broadcasting—Return Channel by Satellite for Next Generation (DVB-RCS NG) and a continuous phase modulation technique, the physical layer specification of DVB-RCS NG requires modification of a burst structure and a demodulation function of a receiving end that is suitable to the modified burst structure.